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Eclipse Bulletin No. 3 cont'd. METHODS OF TIMING (cont'd.). (3) With stopwatch and Short-Wave Radio. Equipped With a stopwatch and short-wave radio, the observer can be his own timekeeper. He starts the watch when the phenomenon occurs and then stops it at a given time signal. By deducting the watch reading from the given time, one obtains tie observed time of the phenon3enon. The stopwatch should be stopped on the next time signal possible, preferably with- in five minutes, for if it is allowed to ran too long, the accuracy of the watch will have to be checked as under (i) above, Method (3) is much more accurate than either (1) or (2) but is dependent on good radio reception, (4) With Short-Wave Radio and Tape Recorder. With radio and tape recorder running continuously, both time signals arid the voice of the observer as he calls "Time!" are it corded on the tape. This method has both advantages anck disadvantages. It can be extremely accurate and the observer can record all other details of this observation on the tape. However, reports are not available immediately. Much playback time is required before written: reports can be produced. Also, because extraneous noise can be a serious handicap, the method is probably better suited to a lone observer than a group effort. It can be seen that the timekeeper is a very important member of the team. Both timekeeper and observer must become thoroughly familiar with the procedure to be foll owed, the equipment end time signals to be used. It is recommended that several drills be held well in advance of eclipse day. REPORT FORMS Attached is a copy of Report Form No I that can be adapted to most observations in this section of the programne ù Where the observer makes a series of observations of the same nAture, such as the occultation of sun-spots, the information could be arranged in tabular form on one report. Otherwise, a separate form should,be completed for each. observation made. (In an drganized field station, some of the work will be centralized such as recording of seeing conditions, etc. thus relieving the indiv- idual observers of the necessity of recording this detail. This will be described in a later bulletin.) EYE PROTECTION It cannot be emphasized too strongly.that where binoculars or telescopes are to be used, extreme care must be taken to protect the eyes during the partial phases,'' for permanent blindness eould result if the eyes are exposed even momentarily to the light of the sun. For binoculars, a welder's glass placed over the objectives would be sufficient. For telescopes, union one has proper solar equipment an objective diaphragm, Herschel wedge and solar eyepiece filter - it is safer to use the projection. method, projecting the sun's image onto. a screen attached by rods to the telescope tube. A SOLAR FILTER ON THE EYEPIECE IS NOT SUFFICIENT It will quickly crack and the eye will be exposed to the sun's heat. Even those who just want to watch fta partial phases of the eclipse with the unaided eye should quip themselves with some protection a piece of heatiiy exposed film or dark glass, preferably welder's glass. - 2 -